CNC Machining Normalizing Steel Parts
Normalizing Service Is a Heat Treatment That Improves The Toughness Of Steel. After Heating The Steel Component To 30 50 Above Ac3 Temperature, It Will Be Heated For a Period Of Time And Air-Cooled Out Of The Furnace.
The Main Characteristics Are That The Cooling Rate Is Faster Than Annealing But Lower Than Quenching. When Normalizing, The Crystalline Grain Of Steel Can Be Refined In a Slightly Faster Cooling Process, Which Not Only Can Obtain Satisfactory Strength, But Also Can Significantly Improve The Toughness (Akv Value), And Reduce The Cracking Tendency Of Components.
After Normalizing Some Low-Alloy Hot-Rolled Steel Sheets, Forgings And Castings, The Comprehensive Mechanical Properties Of The Materials Can Be Greatly Improved, And The Cutting Performance Can Also Be Improved.
Normalizing, Also Known As Normalization, Is The Final Temperature At Which The Workpiece Is Heated To Ac3 (Ac Means The Final Temperature At Which All Free Ferrite Transforms Into Austenite When Heated, Generally From 727 To 912 Degrees c) Or Above 30-50 Degrees Celsius (Acm Is The Critical Temperature Line For Complete Austenitization Of Hypereutectoid Steel In Actual Heating). After Holding For a Period Of Time, The Workpiece Is Removed From The Furnace. Metal Heat Treatment Process In Air Or Water Spray, Spray Or Blow Cooling.
The Aim Is To Refine The Grain Size And Homogenize The Distribution Of Carbides. The Difference Between Normalizing And Annealing Is That The Cooling Rate Of Normalizing Is Slightly Faster Than That Of Annealing, So The Normalizing Structure Is Finer Than That Of Annealing, And Its Mechanical Properties Are Also Improved.
In Addition, The Cooling Outside The Normalizing Furnace Does Not Occupy Equipment, And The Productivity Is High. Therefore, Normalizing Is Used To Replace Annealing As Far As Possible In Production. For Important Forgings With Complex Shape, High Temperature Tempering (550-650 c) Is Needed After Normalizing In Order To Eliminate The Stress Produced During Normalizing Cooling And Improve Toughness And Plasticity.
The Main Applications Of Normalizing Are:
For Low Carbon Steel, The Hardness After Normalizing Is Slightly Higher Than That After Annealing, And The Toughness Is Also Better. It Can Be Used As a Pretreatment For Cutting.
(2) For Medium Carbon Steel, It Can Replace Quenching And Tempering Treatment (Quenching + High Temperature Tempering) As The Final Heat Treatment, And Can Also Be Used As The Preparation Treatment Before Surface Quenching By Induction Heating Method.
(3) Used In Tool Steel, Bearing Steel, Carburized Steel, Etc., Can Reduce Or Inhibit The Formation Of Network Carbides, Thus Obtaining The Good Structure Needed For Spheroidizing Annealing.
(4) It Can Refine As-Cast Structure And Improve Cutting Performance For Steel Castings.
(5) For Large Forgings, It Can Be Used As The Final Heat Treatment To Avoid Large Cracking Tendency During Quenching.
(6) Ductile Iron Is Used To Improve Hardness, Strength And Wear Resistance, Such As Crankshaft And Connecting Rod Of Automobile, Tractor And Diesel Engine.
(7) One Normalizing Before Spheroidizing Annealing Of Hypereutectoid Steel Can Eliminate The Network Secondary Cementite To Ensure That All The Cementite Spheroidized During Spheroidizing Annealing.
Microstructure After Normalizing: Hypoeutectoid Steel Is Ferrite + Pearlite, Eutectoid Steel Is Pearlite, Hypereutectoid Steel Is Pearlite + Secondary Cementite, And Is Discontinuous.
Normalizing Is Mainly Used For Iron And Steel Workpieces. Normalizing Of Steel Is Similar To Annealing, But The Cooling Rate Is Slightly Higher And The Structure Is Finer. Some Steels With Very Low Critical Cooling Rate Can Transform Austenite Into Martensite By Cooling In Air. This Treatment Is Not Normalizing, But Air-Cooled Quenching.
On The Contrary, Some Large Section Workpieces Made Of Steels With Higher Critical Cooling Rate Can Not Obtain Martensite Even When Quenched In Water, And The Quenching Effect Is Close To Normalizing. The Hardness Of Normalized Steel Is Higher Than That Of Annealed Steel. Normalizing Does Not Necessarily Make The Workpiece Cooled With The Furnace As Annealing Does. It Takes a Short Time To Occupy The Furnace And Has High Production Efficiency. Therefore, Normalizing Is Generally Used To Replace Annealing As Far As Possible In Production.
For Low Carbon Steel With Carbon Content Less Than 0.25%, The Hardness After Normalizing Is Moderate, Which Is More Convenient For Cutting Than Annealing. Normalizing Is Generally Used To Prepare For Cutting. For Medium Carbon Steel With 0.25-0.5% Carbon Content, Normalizing Can Also Meet The Requirements Of Cutting.
Normalizing Can Also Be Used As The Final Heat Treatment For Light Load Parts Made Of This Kind Of Steel. Normalizing Of High Carbon Tool Steel And Bearing Steel Is To Eliminate Network Carbides In The Structure And Prepare For Spheroidizing Annealing.
As The Final Heat Treatment Of Ordinary Structural Parts Has Better Comprehensive Mechanical Properties Than Annealing State After Normalizing, Normalizing Can Be Used As Final Heat Treatment For Some Ordinary Structural Parts With Little Stress And Low Performance Requirements, So As To Reduce The Process, Save Energy And Improve Production Efficiency. In Addition, For Some Large Or Complex Parts, When Quenching Is In Danger Of Cracking, Normalizing Can Often Replace Quenching And Tempering Treatment As The Final Heat Treatment.